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Another Distributor Question. HELP!

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lesingepsycho

Jedi Warrior
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OK, I've noticed lately that my distributor has been making a funny chirping/rattling sound usually above 2200RPM. Sounds a little bit like the sound of bad bearings. You know that high-pitched metal jingly sound. I had been nervous about taking it out because the timing was on pretty good and the car has been running well. I finally broke down and pulled the dizzy (after careful indexing) and to my surprise, I found very little play in the shaft. However, when I put the dizzy back in the car, I rotated the shaft left and right and there seemed to be quite a bit of play. Anybody have an idea what the problem might be and any possible solutions? I thought I might just ignore it since the car is running well and then I had visions of a broken timing chain and a fully destroyed engine/pistons/valve-train. /ubbthreads/images/graemlins/cryin.gif
 
[ QUOTE ]
OK, I've noticed lately that my distributor has been making a funny chirping/rattling sound usually above 2200RPM. Sounds a little bit like the sound of bad bearings.

However, when I put the dizzy back in the car, I rotated the shaft left and right and there seemed to be quite a bit of play.

[/ QUOTE ]
If you mean that when you turn the rotor on top it rotates back & forth some, this may be normal.

The centrifugal advance under the breaker plate, rotates the upper (breaker cam) part of the shaft to advance timing as rpm rises. The advance mechanism is spring returned to the retarded position. The top part (with the rotor on it) should rotate in the forward direction about 20 degrees against spring pressure & be returned back to it's rest position by the springs under the breaker plate.

If it (the cam & rotor) are just staying put when you move it, the return springs may be off the track, broken, missing, or stretched & the centrifugal weights that the springs are supposed to hold pressure against may be flopping around & rattling. The chirping could be lack of lube on the cam spindle, the centrifugal weight pivots, or the cam against the point rubbing block. All of these parts need a slight bit of lube.
D
 
What kind of lube should I use on those parts. When I installed my new points they were chirpping away like a cricket on crack and so I just put a dab of all-purpose grease on the cam, that seemed to quiet that problem down for awhile but yes, I forgot to check underneath the breaker plate. That will be the next step. Still keeping my fingers crossed that it is somthing simple in the dizzy!! Thanks! /ubbthreads/images/graemlins/cheers.gif
 
I'm not sure that it matters very much what kind of lube you use. Point sets used to come with a little gelatin capsule full of cam lube. The most important thing is to have something that won't fly off the cam into the points, & use a very small amount. Also use a couple of drops of motor oil in the top of the spindle. Some distributors have a small felt washer on top of the shaft under the rotor cap to hold the oil.
D
 
Well, I cracked open the dizzy again and lifted the breaker plate. It took quite a bit of coaxing to get the upper part of the shaft off because the slot head screw is half rounded off. Once I got under there every thing seemed pretty normal. One of the fly-weights seemed a bit loose, I suppose that could be what's causing the noise. I lubed everything up and buttoned it all back together and stuck it in the car.... nothing. /ubbthreads/images/graemlins/shocked.gif Oh God, what did I do.... /ubbthreads/images/graemlins/shocked.gif everything was running fine and now it's not running at all. /ubbthreads/images/graemlins/cryin.gif How could I have changed the timing? It can't be 180deg. out... it only goes one way.... oh wait. the upper shaft piece isn't keyed. Turns out I had put the shaft together 180deg out. swapped it around and it ran again but still the noise, d'oh!! /ubbthreads/images/graemlins/confused.gif Oh well, I guess I'll keep driving it until either the light bulb goes off in my head or something blows up. /ubbthreads/images/graemlins/confused.gif
 
One of the fly weight springs should be "looser" than the other. If you look carefully, there is a lighter spring which comes into action immediately. The other, heavier, spring is a little longer & doesn't come into action until the cam has advanced somewhat. This gives a somewhat more rapid initial advance & then the rate is slower once the heavier spring also comes into play. Two stage centrifugal advance. Almost universally used.
D
 
I noticed the different size springs and eventually deduced that it was for a 'staged' advance curve. However, that still doesn't explain the noise. Perhaps I'll swap out my dizzy with my moms and see if that gets rid of the noise. If it does then I'll look into it further, if it doesn't, then I'll start looking elsewhere. Also, I have a vacuum unit in the dizzy but it is not hooked up. How should I set the adjuster on the back? Right now I have it screwed all the way in and the car seemed to be running well that way. Will it make any difference if the vacuum isn't hooked up? It seems like even without the vac line hooked up the vac unit changes the position of the breaker plate in relation to the shaft and therefore will change the advance curve of the centrifugal unit. Am I on the right track here or out in left field? I figured by screwing it all the way in, it takes any tension off of the vac unit spring and therefore will not impede the cetrifugal advance in any way.
 
Hmm - The vacuum advance rod has a threaded adjuster on it. With no vacuum, the vacuum advance spring holds the distributor in it's retarded position. You can use this adjuster to advance or retard the timing a few degrees without having to rotate the distributor. It changes the static advance setting but does not change the centrifugal advance characteristics which are in addition to the static setting. It moves the static position of the breaker plate. I would set the timing to 8 degrees before tdc or whatever is called for, with the screw knob in its mid position, & by rotating the distributor. Then fine tuning, about plus or minus three degrees can be done with the little adjuster knob. Any advance by the vacuum unit will be in addition to the static plus centrifugal advance. Clear as mud?
D
 
Hello Dave,
there seems to be a lot of discussion currently about distributors, I have had very little to do with American cars, but are their distributors so different? Or is that a lot of the queries are due to the fact that these member are doing their first practical car maintenance on British cars?

Alec
 
Hi Alec,
I've been doing alot of the posting about dizzies. It's not that I have little experience with them, in fact I have quite alot of experience with them, American and British. The issue with the Lucas dizzy I have in my Midget is that it always seemed like the weak spot in the whole system and is also the hardest to check. The A-series engine has always seemed like a solid performer (despite consuming large amounts of oil) and the carbs, when rebuilt proper and maintained seem to be alright, but the diz has never been a friend of mine. On all the American cars that I have experience with, ignition timing is really easy to check. Generally the timing marks are on the top of the crank pulley with very visible pointers. You can stand looking down into the engine with a strobe in one hand and the other hand on the dizzy making slight adjustments until you get the timing spot on the specs. You can then do vac timing, advance timing, etc all very easily. However, this has never been the case for me with my Midget. There is no way to get a strobe on the timing marks AT ALL that anyone has ever mentioned to me (and I've asked anyone who knows anything about brit cars) because there is a frame crossmember that travels right in front of where the timing marks are located, which, in the genius of British engineering (no offense) is directly on the BOTTOM! I've wondered if perhaps it was set up that way so that you could strobe the car if it was on a rack but actually, the crossmember blocks the view even worse from below. So now, due to this design flaw, one is forced to compromise. In short term fixes, one can set the static timing and just assume that the advance curve is correct (but we all no what happens when you ass-u-me). Otherwise, for a long term fix one must find TDC, then fabricate some sort of pointer and affix it to the timing chain cover or somewhere on the top side of the engine and then make a mark on the pulley and hope that everything isn't starting off misaligned by a degree or two from the get-go. Then you throw into the mix all the loose tolerances that all the british parts were manufactured with and you have a whole circus of problems, noises, bugs, jingles, misses, etc. I have now part-for-part gone through my dizzy and it is still making noises above 2200RPM. The best I can figure is the sloppy wholes that that the pins fit into for the centrifugal advance. I've never had that sort of problem with an American diz but I can only speak from my own experiences.
 
Hi Alec,
It is probably some of each. Although Lucas used some of the same basic methods, they accomplished the details in a manner NOT typical of US designed distributors. It is likely that a lot of folks have had their major experience, up to now, with US designed engines. For some, it may be the first time into British cars. Also US cars have not had points since the early to mid 70's & many distributors have not had mechanical advance for nearly as long. Unless you are pretty old, it requires working on designs which people have never "seen" before. Most of the older LBC's have designs that haven't changed significantly since the 1930's. Way before the younger members were even born. They have to learn "old" technology.

An example would be the BN1 healeys. They don't even "have" timing marks. The owners manual suggests road testing to set timing to "best effect".
D
 
Hello LSP,
I can't begin to imagine why timing marks should be on the bottom. Personally I would make up a pointer and mark the pulley. The noise you refer to is uncharacteristic and I have no idea what it may be, particularly as you have already looked inside.

Alec
 
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